. >> reporter: hundreds turned out to bury mohammed hilal, to mourn the loss of a 22-year-old student who gave out polio vaccine in his spare time. but they also came to express public outrage at this week's murders. nine young people, six of them women, one just 17, have been gunned down since monday, and not at random. a series of coordinated assassinations targeting an annual three day polio vaccination campaign. >> ( translated ): we go out door to door and risk our lives to save innocent children from being permanently handicapped. for what? so that our coming generations turn out to be healthy. we work for our country and we are being rewarded in the form of death. what kind of justice is this? why are we targeted and killed? >> reporter: until someone claims responsibility, we won't know why. the taliban haven't come forward, but extreme islamist groups have long opposed western health interventions and the role for women in campaigns. frustration is compounded by the fact they were making such good progress. there were just 56 cases of polio in pakistan this year, the lowest e